This application claims all benefits accruing 35 U.S.C 119 from the Japanese Patent Application No. 2000-72875, filed on Mar. 15, 2000.
1. Field of the Invention
The present invention relates to a lock switch apparatus used as a safety door switch and the like.
2. Description of the Related Art
A safety door switch is mounted on a safety door for a machine and a door for a protective fence to prevent an accident caused by an inadvertent operation or accidental erroneous operation on various types of machine tools and industrial machines.
The safety door switch serves as an interlocking switch of a machine tool. For example, an operation key is installed on the door side and a switch body is installed on the fixed frame side of a doorway. When the door is closed, the operation key is inserted in the switch body so that an internal switch is turned on, whereby a drive start state is established. Inversely, by performing an operation for opening the door, that is, by removing the operation key from the switch body to turn off the internal switch, the machine tool is placed in the stopped state.
Generally, the lock switches are of two types: a mechanical lock type and a solenoid lock type. A key switch body of a lock switch S of a mechanical lock type has, as shown in FIG. 18(1), a head unit 80xe2x80x2, a detection switch unit 81, a lock unit 82 for locking the detection switch unit 81 in an on state, a solenoid 83 for releasing a lock set by the lock unit 82, and a switch unit 83-1 for detecting the release of lock effected by the solenoid 83.
As shown in FIG. 18(2), by inserting an operation key 76xe2x80x2, a lock of a cam 84 is released, and the cam 84 is turned. Thereby, a second plunger 86, which is connected to a first plunger 85 being in slidable contact with the cam 84, is moved toward a head 80xe2x80x2 by the urging force of a return spring 70xe2x80x2. As a result, a contact face 86A at the end of the second plunger 86 retracts from a plunger guide portion 88 into a guide wall portion 71.
Thus, the second plunger 86 is placed in a state of moving to the maximum. In the detection switch unit 81, therefore, a movable contact 87a of a first movable element 87 comes into contact with a fixed contact 89a of a first fixed terminal 89, whereby a first switch 90 is placed in an on state. Also, a movable contact 91a of a second movable element 91 is separated from a fixed contact 92a of a second fixed terminal 92, whereby a second switch 93 is placed in an off state. Thereby, it is verified that the detection switch unit 81 is operated.
In this case, a third plunger 96 of the lock unit 82 is advanced by the urging force of a locking spring 97, so that the third plunger 96 comes into contact with the contact face 86A at the end of the second plunger 86, by which the detection switch unit 81 is locked in an on state.
As shown in FIG. 18(3), the solenoid 83 is energized to retract a fourth plunger 94 connected to an iron core member 83a and thereby to turn a lever 95 around the turning center P, by which the third plunger 96 is moved against the locking spring 97. Thereby, the third plunger 96 is removed from the contact face 86A at the end of the second plunger 86 to release the lock of the detection switch unit 81.
In this case, by the movement of the fourth plunger 94, in the switch unit 83-1, a movable contact 98a at both ends of a movable element 98 is separated from a fixed contact 99a of a fixed terminal 99, so that a switch-off state is established. Therefore, since the switch unit 83-1 is placed in a switch-off state, the release of lock effected by the solenoid 83 is detected.
Also, by removing the operation key 76xe2x80x2, the cam 84 is pulled by means of a transverse member 77a of the operation key 76xe2x80x2 to turn the cam 84 reversely. By the reverse turning of the cam 84, the second plunger 86, which is connected to the first plunger 85 being in slidable contact with the cam 84, is moved to the direction opposite to the head 80xe2x80x2 against the return spring 87, so that the contact face 86A at the end of the second plunger 86 projects into the plunger guide portion 88.
In the detection switch unit 81, the movable contact 87a of the first movable element 87 is separated from the fixed contact 89a of the first fixed terminal 89, so that the first switch 90 is placed in an off state. Also, the movable contact 91a of the second movable element 91 comes into contact with the fixed contact 92a of the second fixed terminal 92, so that the second switch 93 is placed in an on state.
As shown in FIGS. 19(1), 19(2) and 19(3), a lock switch S-1 of a solenoid lock type is different from the lock switch S of a mechanical lock type in that an unlocking spring 97-1 is disposed in place of the locking spring 97 to release the lock of the third plunger 96 in the lock unit 82. In this lock switch of a solenoid lock type, when the solenoid 83 is in an off state, a lock is not set, and only when the solenoid 83 is in an on state, a lock is set as shown in FIG. 19(3). Other configurations are the same as those of the lock switch S of a mechanical lock type.
However, the above-described conventional lock switch apparatus has a construction such that the third plunger 96 is connected to the fourth plunger 94, which is connected to the iron core member 83a of the solenoid 83, via the lever 95. Therefore, in order for the solenoid 83 to develop an attraction, a large-sized solenoid 83 is needed, which leads to an increased size and cost. Also, in the case where a vibration or impact is applied to the switch body, if the iron core weight increases in the large-sized solenoid 83, the iron core is moved under the influence of an inertia force, easily causing a malfunction of switch signal, which presents a problem in that a malfunction of the apparatus occurs.
Also, in the case of the lock switch S-1 of a solenoid lock type, since a lock must be set during the time when the apparatus is operated, the solenoid 83 must always be energized during this time, so that electric power is continuously consumed, which presents a problem in that the equipment cost increases.
The present invention has been made paying attention to the above problems, and accordingly an object thereof is to provide a lock switch apparatus in which a small-sized solenoid can be used, so that the outside size of a switch can be decreased, whereby handling by the user can be made easy.
The present invention provides a lock switch apparatus comprising: a key insertion unit; a detection switch unit for detecting the insertion of an operation key in the key insertion unit; a lock unit for locking the operation key when the operation key is inserted in the key insertion unit; and a lock detection unit for detecting the operation state of the lock unit, wherein the detection switch unit has a plunger which is moved by the insertion of the operation key in the key insertion unit to operate a switch element, the lock unit has a slide lock member for locking the plunger by the movement thereof and a solenoid for operating a solenoid-side movable portion by being energized, the solenoid-side movable portion of the solenoid is connected to the slide lock member by a lever having a turning center in an intermediate portion thereof, and the slide lock member is moved at the ratio of the lever with respect to the operation of the solenoid-side movable portion, whereby the plunger is locked.
By the above-described configuration, the plunger can be locked by moving the slide lock member at the ratio of the lever with respect to the operation of the solenoid-side movable portion. Therefore, the slide lock member can be moved by using the solenoid-side movable portion in a zone in which the attraction of the solenoid is large.
Therefore, a small-sized solenoid can be used, so that the outside size of the lock switch apparatus can be decreased, whereby a switch capable of being handled easily by the user can be realized.
Also, the present invention provides a lock switch apparatus comprising: a key insertion unit; a detection switch unit for detecting the insertion of an operation key in the key insertion unit; a lock unit for locking the operation key when the operation key is inserted in the key insertion unit; and a lock detection unit for detecting the operation state of the lock unit, wherein the lock unit is configured so that the operation key is locked by the attraction of a solenoid, a movable system of a solenoid-side movable portion is configured by providing an associatively movable portion which moves in association with the solenoid-side movable portion with respect to the solenoid-side movable portion of the solenoid, and vibration/impact absorbing means is provided to provide a balance state of operating forces applied to the movable system. By the above-described configuration, the balance of the operating forces applied to the movable system is maintained by the vibration/impact absorbing means. Therefore, when a vibration or impact is applied to the lock switch apparatus, the movable system does not move, and a malfunction of switch signal due to an inertia force of the movable system, especially, the solenoid-side movable portion of the solenoid can be prevented, and also the lock switch apparatus can be made small in size.
Also, in the lock switch apparatus in accordance with the present invention, the associatively movable portion of the vibration/impact absorbing means includes the slide lock member which moves in association with the solenoid-side movable portion of the solenoid at the ratio of a lever, and the travel amount of the solenoid-side movable portion is amplified at the ratio of the lever to secure the travel amount of the slide lock member.
By the above-described configuration, the travel amount of the slide lock member can be secured by amplifying the amount of travel of the solenoid-side movable portion caused by the attraction of the solenoid at the ratio of the lever. Therefore, the slide lock member can be moved by using the solenoid-side movable portion in a zone in which the attraction of the solenoid is large.
Thereupon, a small-sized solenoid can be used, so that the outside size of the lock switch apparatus can be decreased, whereby a switch capable of being handled easily by the user can be realized.
Also, in the lock switch apparatus in accordance with the present invention, the lock switch apparatus has lock holding force securing means for holding and securing a lock holding force of the lock unit by mechanical means without dependence on the attraction of the solenoid.
Also, two stationary points of the slide lock member at the time when the solenoid is de-energized are provided in the travel direction of the slide lock member, and what we call an alternate operation, in which the stationary points are changed over alternately when the solenoid is turned on, off, and on, is performed, so that a lock state of the operation key is established at a first stationary point, and an unlock state is established at a second stationary point.
By the above-described configuration, the alternate lock state, that is, a mechanically locked state can be established. Therefore, power consumption during the operation of the apparatus can be eliminated, which contributes to power saving of the whole system. Also, the influence of deterioration in characteristics due to heat of the solenoid can be decreased, so that a switch with high reliability can be provided by being operated in a superior characteristic zone.
Also, in the lock switch apparatus in accordance with the present invention, the lock switch apparatus has compulsorily unlocking means for releasing lock hold caused by the lock holding force securing means by using mechanical means without dependence on the attraction of the solenoid.
By the above-described configuration, the lock can be released and the state can be returned from the alternate lock state, that is, the mechanically locked state to the initial state artificially without energizing the solenoid.
Also, in the lock switch apparatus in accordance with the present invention, the lock detection unit carries out the detection of a lock state caused by the attraction of the solenoid and a mechanical lock hold state independently of each other.
By the above-described configuration, the detection of the lock state caused by the attraction of the solenoid and the detection of the mechanical lock hold can be distinguished from each other, so that a difference in lock can be recognized by the user.
Also, in the lock switch apparatus in accordance with the present invention, the detection switch unit is disposed on one face of a base member, and the lock unit, the lock detection unit, and the vibration/impact absorbing means are disposed on the other face of the base member.
By the above-described configuration, the outside shape of the switch can be made square, so that a degree of freedom can be provided when the switch is installed.